The present invention relates to circuit breakers and more particularly to a safety device and/or to a device for signaling the triggered state of a circuit breaker.
In order to detect current surges, circuit breakers comprise an element, such as a bimetal blade, subject to deformation when it is heated by the passage of a current. Generally, the triggering device includes a main bimetal blade coupled by a connecting rod to a compensation bimetal blade associated with triggering means. The main bimetal blades of circuit breakers generally comprise an end fixed to the circuit breaker housing and a free end which is adjusted to a predetermined rest position determining the triggering surge value of the circuit breaker. This predetermined position is generally obtained by adjusting the inclination of the bimetal blade by a perpendicular screw abutting against the bimetal blade and screwed in the housing of the circuit breaker. The fixed end of the bimetal blade is conventionally directly welded to an input connector fixed to the circuit breaker housing.
A drawback of this configuration is that constraints external to the circuit breaker may deform the input connector and consequently alter the bimetal blade position. These external constraints may, for example, occur when a screw is tightened to fix a cable to the connector.
Some circuit breakers are provided with a signaling device for indicating to an operator that the circuit breaker is at the triggered state. Generally, circuit breakers comprise a fixed contact and a movable contact associated with a control mechanism for applying the movable contact onto the fixed contact when the circuit breaker is set and for causing the reverse movement when the circuit breaker is triggered. Signaling devices are conventionally controlled by the triggering movement of the control mechanism. However, contacts may remain sticked together due to a surge. In order to be sure that the circuit is interrupted even in that case, an element in the current path, for example a bimetal blade, is provided to act as a fuse. But, since the contacts have not been separated, the control mechanism remains blocked and does not activate the signaling device. Hence, an operator cannot know whether the circuit has been interrupted.
Multipolar circuit breakers for multiple phased currents generally include a pair of contacts per phase. These contact pairs cooperate with a single control mechanism so that all the phases are interrupted when a surge occurs in one of the phases. If, during a surge, one of the contact pairs remains in contact, as in the above example, the control mechanism remains blocked and the contact pairs associated to the other phases also remain in contact, which is undesirable.
An object of the invention is to provide a device for signaling the triggered state of the circuit breaker which is still operational even when contacts remain in contact.
Another object of the invention is to provide a safety device incorporated in a multipolar circuit breaker which separates the other contacts, in case one of the pairs of contacts remains in contact following a current surge.
These objects are achieved with a circuit breaker comprising a lock having a high position when the circuit breaker is triggered and a low position when the circuit breaker is set, the lock in the low position being held by a locking lever against which the lock abuts, the lever cooperating with a device for detecting a current surge which, during a surge, disengages the lever so that the lock no longer abuts against the lever and is released in order to go back to its high position. The locking lever is movable between a high position and a low position. The lever is urged to its low position when the lock is set to low position and is associated with upward biasing means active when the lock no longer abuts against the lever.
According to an embodiment of the invention, the circuit breaker comprises a contact for signaling the triggering of the circuit breaker, the contact being associated with closing means active when the locking lever is at its high position.
According to an embodiment of the invention, the locking lever abuts at its high position against an end of a lever, the other end of which closes the contact.
According to an embodiment of the invention, the circuit breaker comprises a plurality of similar triggering mechanisms and means for simultaneously triggering these mechanisms when the locking lever is at its high position.
According to an embodiment of the invention, each locking lever at its high position abuts against one end of a second lever fixed to an axle on which similar second levers are fixed, the other ends of these second levers disengaging the locking levers from the other mechanisms of the circuit breaker in order to release the associated locks.
According to an embodiment of the invention, the surge detecting device comprises a main bimetal blade, substantially vertical, the base of which is fixed to the circuit breaker housing, a compensation bimetal blade, substantially vertical, the base of which is articulated to the housing and a connecting rod sliding between the upper ends of the bimetal blades, the compensation bimetal blade being disposed so as to disengage the locking lever when the main bimetal blade is sufficiently bent.
According to an embodiment of the invention, the upward biasing means comprises a spring disposed in slots opening at the bottom of the locking lever, the spring pressing between a part fixed to the housing and the interior of the slots.